package com.example.mungaddresslist;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private MyHelper myHelper;
    private EditText mEtName;
    private EditText mEtPhone;
    private TextView mTvShow;
    private Button mBtnAdd,mBtnQuery,mBtnUpdate,mBtnDelete;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myHelper=new MyHelper(this);
        init();
    }

    private void init() {
        mEtName=(EditText) findViewById(R.id.et_name);
        mEtPhone=(EditText) findViewById(R.id.et_phone);
        mTvShow=(TextView) findViewById(R.id.tv_show);
        mBtnAdd=(Button) findViewById(R.id.btn_add);
        mBtnQuery=(Button) findViewById(R.id.btn_query);
        mBtnUpdate=(Button) findViewById(R.id.btn_update);
        mBtnDelete=(Button) findViewById(R.id.btn_delete);
        mBtnAdd.setOnClickListener(this);
        mBtnQuery.setOnClickListener(this);
        mBtnUpdate.setOnClickListener(this);
        mBtnDelete.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        String name,phone;
        SQLiteDatabase db;
        ContentValues values;
        switch(view.getId()){
            case R.id.btn_add:  //添加数据
                name=mEtName.getText().toString();
                phone=mEtPhone.getText().toString();
                db=myHelper.getWritableDatabase();
                values=new ContentValues();
                values.put("name",name);
                values.put("phone",phone);
                db.insert("information",null,values);
                db.close();
                Toast.makeText(this,"信息已添加到数据库中",Toast.LENGTH_LONG).show();
                break;
            case R.id.btn_query: //查询数据
                mTvShow.setText("");
                db=myHelper.getReadableDatabase();
                Cursor cursor=db.query("information",null,null,null,null,null,null);
                if(cursor.getCount()==0){
                    Toast.makeText(this,"没有数据",Toast.LENGTH_LONG);
                }else{
                    cursor.moveToFirst();
                    mTvShow.setText("Name: "+cursor.getString(1)+"  Tel: "+cursor.getString(2));
                    while(cursor.moveToNext()){
                        mTvShow.append("\nName: "+cursor.getString(1)+"  Tel: "+cursor.getString(2));
                    }
                }
                cursor.close();
                    db.close();
                break;
            case R.id.btn_update:
                name=mEtName.getText().toString();
                phone=mEtPhone.getText().toString();
                db=myHelper.getWritableDatabase();
                values=new ContentValues();
                values.put("phone",phone);
                db.update("information",values,"name=?",new String[]{name});
                db.close();
                Toast.makeText(this,"信息已修改",Toast.LENGTH_LONG).show();
                break;
            case R.id.btn_delete:
                db=myHelper.getWritableDatabase();
                db.delete("information",null,null);
                mTvShow.setText("");
                db.close();
                Toast.makeText(this,"信息已删除",Toast.LENGTH_LONG).show();
                break;
        }
    }
    //创建MyHelper内部类
    class MyHelper extends SQLiteOpenHelper{
        public MyHelper(@Nullable Context context) {
            super(context, "Addrlist.db", null, 1);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL("CREATE TABLE information(_id INTEGER PRIMARY KEY AUTOINCREMENT,name " +
                    "VARCHAR(20),phone VARCHAR(20))");
        }

        @Override
        public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

        }
    }
}
